Median age 49 years. All patients were stage III or IV, never previously treated. 71% were small cleaved cell while 29% were follicular mixed cellularity. 63% had positive bone marrow and 31% had elevated LDH.

Bexxar was administered according to the standard protocol as previously described by Kaminski. Briefly, an initial dosmetric dose of 5 mCi was administered in order to determine the therapeutic dose required to provide a total body dose of 75 cGy. This dose was delivered in a single administration.

94% of patients PCR (+) for the t(14;18) translocation at enrollment became PCR negative after treatment.

Primary side effect was myelosupression. Median neutrophil nadir was 1,300; median platelet nadir was 83,000. No patients required transfusion or growth factor support

Hypothyroidism was the other main toxicity. Estimated 4 year incidence of hypothyroidism was 12%.

63% of patients developed human anti-murine antibodies, possibly limiting future retreatment with Bexxar. This is significantly higher than the 10% rate seen previously in trials of patients with relapsed or refractory LG NHL.

No incidence of myelodysplastic syndrome at median follow-up of 2.6 years.

The initial treatment of low grade lymphoma remains controversial. The data presented in this trial provide support for the use of molecularly targeted therapies such as Bexxar in the first line treatment for LG NHL. Bexxar leads to a high response rate in treatment naive patients with a low incidence of associated side effects, especially when compared to conventional cytotoxic chemotherapy. Phase III trials are necessary in order to further define the utility of Bexxar as first line therapy and to clarify the significance of the rather high incidence of human anti-murine antibody production, which may limit the potential of Bexxar retreatment.

Oncolink's ASH Coverage made possible by an unrestricted Educational Grant from Ortho Biotech.